The Invisible Layer We Forgot to Protect When most people talk about Web3 security, they usually think of smart contracts. And that makes sense. After all, these snippets of code hold real assets, define protocol logic, and protect billions of dollars of user funds. For years, security teams have devoted endless effort to finding reentrancy vulnerabilities, access control issues, arithmetic errors, and subtle vulnerabilities that only appear under specific execution paths. But in all this obsession with what happens on-chain, we’ve overlooked the first thing that the vast majority of users actually interact with: the frontend. The frontend has always been seen as the shiny shell, the interface that helps users talk to the blockchain. But this “shell” is quickly becoming one of the most abused layers in the entire ecosystem. While smart contracts are immutable and auditable, frontends are mutable, centralized, and served by infrastructure that is completely outside the blockchain’s assurances. Yet, they are the ones that build the transaction payloads that wallets ask users to sign. If that doesn’t scare you yet, it should.
Trusting the Interface Means Trusting the Attacker
The real danger with frontends isn’t necessarily technical complexity; it’s misplaced trust. Most users don’t know what they’re actually signing when they confirm a transaction. They rely entirely on what the frontend shows them.
A “Swap” button might be triggering an approval. A staking interface might be passing a delegate call. Unless wallets decode the data in a human-readable format, and many wallets still don’t, users can’t verify what they’re doing.
This makes frontend hacking one of the most effective ways to steal funds in Web3. Attackers don’t need to break contracts or find vulnerabilities in the core protocol. All they need is a way to tamper with the frontend, even temporarily, and they can sit invisibly between the user and the blockchain. Every click becomes an opportunity for hijacking intent.
How These Attacks Happen
There’s nothing special about how these attacks are carried out. Sometimes it’s as simple as a DNS hijack, where an attacker gains access to a project’s domain name records and points them to a malicious server. In other cases, attackers inject code through infected dependencies, replacing malicious logic and modifying transaction data before it’s passed to the wallet. In still other cases, the frontend is compromised directly through access to a cloud dashboard or CDN configuration, allowing attackers to change UI scripts in real time.
The effect is always the same. The user accesses the application as usual, connects their wallet, and signs a transaction they believe is safe. But what they sign is something completely different, usually approval of an untrusted contract or the transfer of tokens to a wallet controlled by the attacker. And because the blockchain executes exactly on the signature, there’s no undo button.
Recent events demonstrating this
We've seen some painful examples of this. One of the most notable examples was the Curve Finance incident in 2022, where attackers took control of Curve's DNS and presented a fake frontend to users. The website looked exactly the same. The wallet prompts looked normal as well. But behind the scenes, every transaction was being routed to the attacker's wallet. Nearly $600,000 was lost in just a few hours.
Another example was the BadgerDAO, which lost over $100 million after attackers injected malicious JavaScript into its frontend. The code quietly changed transaction payloads for specific users (especially whales), leaving those users to click their way to ruin.
What these incidents have in common is that the smart contracts remained unchanged. The logic was sound, the audits were clean, but none of that mattered when the frontend told a different story.
Why This Problem Won’t Go Away
What makes frontend security particularly difficult in Web3 is that it falls into a weird grey area. It’s off-chain, so most on-chain security tools can’t monitor it. It’s often overlooked during audits, especially in projects that prioritize delivery over security. And it relies heavily on centralized infrastructure like DNS, cloud storage, and JavaScript package registries, none of which offer the same guarantees as blockchains.
To make matters worse, the tooling around frontend validation is still immature. Unlike contract bytecode, which can be verified on-chain, frontend code changes frequently, is rarely pinned or hashed, and is almost never released in a way that users can inspect. This creates a perfect environment for targeted attacks, especially during sensitive times like token launches, airdrops, or UI upgrades.
What Needs to Change
For Web3 to evolve safely, security needs to extend beyond smart contracts. Developers must treat the frontend with the same paranoia and rigor as they do the backend. This means locking down dependencies, avoiding unnecessary third-party scripts, securing DNS configurations, and considering frontend audits as part of every major release.
Wallet providers should also play a role. Users need to have greater clarity about what they are signing. This could mean improved decoding, better warnings, or even frontend authenticity checks. Right now, there is too much trust in interfaces and not enough effort to verify their integrity.
From a user’s perspective, the advice is harsh but honest:
Don’t trust any UI blindly. If you’re interacting with a high-value protocol, don’t just check the domain name. Check the source code. Use a browser extension that tracks malicious contracts. If something doesn’t feel right, don’t sign.Conclusion
Web3 isn’t just about trustless execution. It’s about the entire trust boundary, where it starts, how it shifts, and where it ends. Right now, frontends sit right in the middle of that boundary, and have become a playground for anyone smart enough to exploit the gap between what the user sees and what they sign.
Your contract may be perfect, but if your frontend is compromised, the result is the same.
Funds are lost, trust is broken, and users are left wondering how it all went wrong. It’s time for the industry to stop treating the front end as an afterthought. Because for hackers, it has become the first target of their attack.
Hui Xin
Joy
Clement
Catherine
Kikyo
Davin
Jasper